highlight changes in chrome

2019-12-26

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~1 min read

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173 words

When React Dev Tools v4 landed the feature to highlight updated components disappeared.

It’s true that focusing only on re-renders can be inappropriate as Dan Abramov explains on Reddit:

[Highlight Updates] contributes to the wrong idea that re-renders by themselves are bad (they’re not if they’re cheap). So people spend time optimizing useless things and missing actual performance issues.

None the less - it can be useful to quickly check whether components are rendering as expected.

In looking for an alternative, I discovered that the Chrome dev tools actually have a very similar feature (albeit not React specific) as part of their performance analyzing suite.

Quick steps to use turn it on:

command palette

  1. Open your dev tools (⌥ Alt + ⌘ Cmd + I)
  2. Open the Command Palette (⌘ Cmd + ⇧ Shift+P) in the dev tools.
  3. Turn on “Show Rendering”

rendering options

  1. Select the options you want

rendering in action

  1. Update the page and watch it paint live.

(Update Highlights were brought back in React Dev Tools v4.2. Woohoo!🎉)


Hi there and thanks for reading! My name's Stephen. I live in Chicago with my wife, Kate, and dog, Finn. Want more? See about and get in touch!